Turbo-molecular pump

Abstract

A turbo-molecular pump comprises a rotor having rotor blades and a cylindrical section; stationary blades; a plurality of spacers; a stator arranged with a gap from the cylindrical section, a base; a spacer cooling section arranged between a lowest spacer of the stacked spacers and the base, the spacer cooling section having a first flow passage through which coolant flows; a heater for heating the stator; a temperature sensor for detecting a temperature of the stator; a base cooling section for cooling the base, the base cooling section having a second flow passage connected in series to the first flow passage; and a temperature controller for controlling circulation of coolant to the first flow passage and the second flow passage connected in series and energization of the heater to maintain the temperature of the stator at a predetermined temperature.

What is claimed is: 
     
       1. A turbo-molecular pump comprising:
 a rotor having a plurality of stages of rotor blades and a cylindrical section; 
 a plurality of stages of stationary blades alternately arranged with respect to the plurality of stages of rotor blades; 
 a plurality of spacers stacked to position the plurality of stages of stationary blades; 
 a stator arranged with a gap from the cylindrical section, 
 a base to which the stator is fixed; 
 a spacer cooling section arranged between a lowest spacer of the stacked spacers and the base, the spacer cooling section having a first flow passage through which coolant flows; 
 a heater for heating the stator; 
 a temperature sensor for detecting a temperature of the stator; 
 a base cooling section for cooling the base, the base cooling section having a second flow passage connected in series to the first flow passage; and 
 a temperature controller for controlling circulation of coolant to the first flow passage and the second flow passage connected in series and energization of the heater to maintain the temperature of the stator at a predetermined temperature. 
 
     
     
       2. The turbo-molecular pump according to  claim 1 , wherein
 an outflow section of the second flow passage is connected to an inflow section of the first flow passage to allow coolant to circulate from the second flow passage to the first flow passage. 
 
     
     
       3. The turbo-molecular pump according to  claim 1 , wherein
 an outflow section of the first flow passage is connected to an inflow section of the second flow passage to allow coolant to circulate from the first flow passage to the second flow passage. 
 
     
     
       4. The turbo-molecular pump according to  claim 1 , further comprising:
 a bypass pipe connected in parallel to the first flow passage and the second flow passage connected in series; and 
 a three-way valve for alternatively switching a first circulation state in which coolant circulates to the first flow passage and the second flow passage and a second circulation state in which coolant circulates to the bypass pipe, 
 wherein the temperature controller controls energization of the heater and switching between the first circulation state and the second circulation state performed by the three-way valve to maintain the temperature of the stator at the predetermined temperature.